You are on a bridge which is a height 21 above the water. You first drop a ball and then 1.0 seconds later throw a second ball down so that both balls hit the water at the same time. (assume the positive y-direction is up)
At what time after you release the first ball does it hit the water?
With what velocity must the second ball be thrown downwards?
What is the speed of the first ball just before it hits the water?
What is the velocity of the second ball just before it hits the water?